Solid matrix system for transdermal drug delivery

ABSTRACT

A matrix for containing drugs for transdermal delivery systems is disclosed. The matrix, formed of a skin-adhesive acrylate copolymer, attains high rates of drug delivery without the addition of drug delivery rate enhancers. In preferred embodiments the matrix is used to administer steroids, in particular estradiol. Water-soluble polymers may be added as well.

This application is a continuation of application Ser. No. 07/405,630,filed Sep. 8, 1989, now abandoned.

TECHNICAL FIELD

This invention relates generally to the transdermal administration ofdrugs. More particularly, it concerns a configuration for transdermaldrug delivery devices which enables the administration of effectivelevels of drugs without the necessity for coadministration with skinpenetration rate enhancers.

BACKGROUND

Transdermal delivery of drugs, that is, delivery of drugs through theskin, provides many advantages. The method is a comfortable, convenient,and noninvasive way of administering drugs. Many of the variables andside effects associated with oral administration are eliminated. Sincethe early 1970s, there has been substantial effort spent on developingparticular systems for effectively delivering drugs in a transdermalmode. A variety of devices containing, at minimum, a drug reservoir anda backing, and optionally containing other layers, such as an adhesivelayer for adhering the device to the patient, a drug release ratecontrolling layer for moderating delivery rate, and the like, have beenconstructed. With certain drugs, in particular scopolamine andnitroglycerine, it is feasible to construct a transdermal drug deliverydevice which will achieve therapeutically effective levels of the drugin the patient. Commercial products have been introduced to deliverthese two materials. However, one of the key problems with transdermaladministration of many other drugs has been the low penetration orpermeation rate of drug through the skin of the patient. The researchover the past two decades has identified various skin permeationenhancers. These materials increase the rate of penetration of drugsacross the skin.

Typical enhancers in the art include ethanol, glycerol monolaurate, PGML(polyethylene glycol monolaurate), dimethylsulfoxide, and the like. Manyhighly attractive drugs, such as estradiol, progestins and the like arecommonly formulated with enhancers for transdermal delivery.

The use of permeation enhancers is not without its drawbacks. For one,the permeation enhancer typically is coadministered with the desireddrug. That is, the permeation enhancer passes through the patient's skinat the same time the drug does. Depending upon the exact nature of thepermeation enhancer, this can lead to side effects related directly tothe permeation enhancers.

Another disadvantage is that the enhancers are often organic solvents,which can in some cases react with and alter the character of the drugbeing delivered. In addition, the enhancers can interact with thepatient's skin, in some cases causing irritation and the like. Moreover,enhancers can interfere with the mechanical properties of the devices,such as interfering with the effectiveness of adhesive layers and thelike.

The present invention provides drug-matrix constructions which, whencontacted with patient skin, allow high rates of delivery of drugwithout the necessity of added permeation enhancers previously requiredto reach therapeutic blood levels.

DISCLOSURE OF THE INVENTION

It has now been found that the necessity for incorporating permeationenhancers into drug delivery systems can be reduced or eliminated byincorporating the drug in a matrix comprising a vinyl acetate-acrylatecopolymer and delivering the drug to the patient from this matrix.

This invention can take the form of a transdermal drug delivery devicefor administering a drug to a predetermined area of skin or mucosa of apatient. This device can be made up as a laminated composite thatincludes

(a) a backing layer that is substantially impermeable to the drug anddefines the face surface of the composite, and

(b) a matrix layer made up of a pressure-sensitive vinylacetate-acrylate copolymer forming the bottom surface of the device andwhich serves to adhere the device to the skin or mucosa of the patient,said layer having the drug dispersed therein.

Such a device can give rise to high rates of drug delivery with littleor no added permeation enhancer present.

The invention can also take the form of the matrix itself.

In another aspect, the invention provides a method of transdermal drugdelivery employing the matrix and device of this invention.

In preferred embodiments, the matrix of this device can additionallycontain hydrophilic polymers such as the water-soluble polymers, forexample, polyvinyl alcohol or polyvinyl pyrrolidone.

BRIEF DESCRIPTION OF THE DRAWINGS

This invention will be described with reference being made to theaccompanying drawings, in which:

FIG. 1 is a not-to-scale cross-sectional view of one form of drugdelivery device constructed using the teachings of this invention;

FIG. 2 is a not-to-scale cross-sectional view of a second form of drugdelivery device constructed using the teachings of this invention.

FIG. 3 is a graph illustrating the fluxes attainable in drug deliverysystems employing the present invention.

MODES FOR CARRYING OUT THE INVENTION Definitions

In this specification and claims certain terms will be used which havedefined meanings.

By "transdermal" delivery is intended both transdermal (or"percutaneous") and transmucosal administration, i.e., delivery bypassage of a drug through the skin or mucosal tissue and into thebloodstream.

"Carriers" or "vehicles" as used herein refer to carrier materialssuitable for transdermal drug administration, and include any suchmaterials known in the art, e.g., any liquid, gel, solvent, liquiddiluent, solubilizer, or the like, which is nontoxic and which does notinteract with other components of the composition or the skin in adeleterious manner. Examples of suitable carriers for use herein includewater, mineral oil, silicone, liquid sugars, waxes, petroleum jelly, anda variety of other oils and polymeric materials. In addition, one orboth of the components of the present enhancer composition may alsoserve as a carrier.

"Permeation enhancement" and "permeation enhancers" as used hereinrelate to the process and added materials which bring about an increasein the permeability of skin to a poorly skin permeatingpharmacologically active agent, i.e., so as to increase the rate atwhich the drug permeates through the skin and enters the bloodstream.The enhanced permeation effected through the use of such enhancers isnot required when the matrix compositions of the present invention areemployed.

By the term "pharmacologically active agent" or "drug" as used herein ismeant any chemical material or compound suitable for transdermal ortransmucosal administration which induces a desired systemic effect.Such substances include the broad classes of compounds normallydelivered through body surfaces and membranes, including skin. Ingeneral, this includes: anti-infectives such as antibiotics andantiviral agents; analgesics and analgesic combinations; anorexics;antihelminthics; antiarthritics; antiasthmatic agents; anticonvulsants;antidepressants; antidiabetic agents; antidiarrheals; antihistamines;antiinflammatory agents; antimigraine preparations; antinauseants;antineoplastics; antiparkinsonism drugs; antipruritics; antipsychotics;antipyretics; antispasmodics; anticholinergics; sympathomimetics;xanthine derivatives; cardiovascular preparations including calciumchannel blockers, beta-blockers such as pindolol, anti-arrhythmics,antihypertensives, diuretics,and vasodilators including generalcoronary, peripheral and cerebral; central nervous system stimulants;cough and cold preparations, including anti-histamine decongestants;hormones such as the estrogens estradiol and progesterone and othersteroids, including corticosteroids; hypnotics; immunosuppressives;muscle relaxants; parasympatholytics; psychostimulants; sedatives; andtranquilizers.

Steroid drugs represent a preferred class of drugs for use inconjunction with the drug delivery device and matrix composition of thepresent invention. Steroid drugs have been difficult materials toadminister transdermally, historically because of their generally poor(low) skin permeation properties. Historically, skin permeationenhancers have been used to achieve therapeutic blood levels inpatients. Thus this invention is of special advantage when used withsuch materials. Examples of steroid drugs useful herein include:progestogens such as norethindrone, norethindrone acetate, desogestrel,3-keto desogestrel, gestadene and levonorgestrel; estrogens such asestradiol and its esters, e.g., estradiol valerate, cyprionate,decanoate and acetate, as well as ethinyl estradiol; androgens such astestosterone and its esters; and corticosteroids such as cortisone,hydrocortisone, and fluocinolone acetonide In a particularly preferredembodiment, the devices and matrices of the invention include one ormore estrogens, in particular estradiol, and may include one or moreprogestogens, as well.

By "therapeutically effective" amount of a pharmacologically activeagent is meant a nontoxic but sufficient amount of a compound to providethe desired therapeutic effect.

"Water-soluble polymer" means a hydrophilic polymer having a solubilityin water of greater than 0.1% by weight.

The Matrix Material

A key element of this invention is the use of a matrix which permitshigh delivery rates for drugs without the use of added skin penetrationrate enhancers.

It has been found that matrices made from acetate-acrylate copolymergive rise to unexpectedly high rates of drug delivery. Theseacetate-acrylate copolymer materials are available commercially. Forexample, Monsanto Chemical Company distributes a family of vinylacetate-acrylate copolymer resin solutions under the trademarks GELVA®737 and GELVA® 788 and Morton Thiokol, Inc. distributes acrylatecopolymers under the trademarks Morstik 207A and Morstik 607.

These acrylate copolymer materials can be used separately or inmixtures. Several specific materials which have given rise to superiorresults are the Morstik 607 material, the GELVA® materials, which arebelieved to be based on 2-ethylhexyl acrylate, and mixtures of fromabout 20:1 to about 1:1 parts GELVA® 737 and GELVA® 788 (ratios given asweight ratios of GELVA® 737 to GELVA® 788). All of these materials aresolvent based but form films following casting and removal of thesolvent. The term "solid" is used broadly since the "solid" product isgenerally a tacky, amorphous (i.e. pressure sensitive adhesive)non-flowing material.

These materials are typically available as solutions in organic solventssuch as toluene, ethanol, isopropanol, ethyl acetate and the like. Thesesolvents are substantially eliminated from the matrix duringfabrication.

These copolymers have the property of being high tack pressure sensitiveadhesive when dried and/or cured. Thus, the matrices formed from thesematerials can adhere directly to the patient's skin without the need foradditional separate adhesives.

Devices and Device Fabrication

The devices of this invention include a solid body of the matrix-formingcopolymer material throughout which the drug is incorporated. Thisincorporation can be carried out by simply dissolving or otherwisefinely dispersing the drug in a solution of the matrix material to yielda solution or slurry, casting the slurry or solution that contains thedrug matrix and then evaporating the volatile solvents to give a solidmatrix with drug incorporated therein.

The incorporating can be carried out with conventional polymersolution-handling equipment such as mixers, mills or the like, and canbe completed in from a few seconds to a few hours, depending upon mixingconditions. Generally, it is continued until a uniform solution orhomogeneous dispersion is attained.

Although not known with certainty and without intention to be bound toany particular mode of operation, it is believed that the high drug fluxrate obtained using the matrices of this invention may in part resultfrom the fact that the drug is contacted with the matrix-formingsolution prior to solidification. This contact may result in at leastpartially dissolving the drug in the matrix phase, changing the drug'scrystalline form to a more polymorphic structure, or forming amicrodispersion of the drug in the matrix polymer.

The casting can be carried out using manual casting machines or doctorblades or the like or can be carried out with commercial film castingequipment for large scale production.

The thickness of the matrix can vary from 10 micrometers to about 250micrometers. Preferred thicknesses are from 15 to 100 micrometers. Theserelatively thin layer thicknesses are of advantage in assuring thecompleteness of the subsequent solvent removal step.

The solvent removal should be thorough and is carried out using heat,air flow and/or a vacuum. Temperatures should be held below temperaturesat which significant degradation of drug occurs and typically range fromroom temperature (approximately 20° C. to 25° C.) to about 100° C.although higher temperatures can be used if the nature of the drugpermits.

The solvent removal should be carried out completely until nosubstantial solvent remains, for example until the solvent level is lessthan 5%, preferably less than 1% by weight.

As shown in FIG. 1, the device 10 of this invention includes a matrix 11having drug dispersed therethrough and can in addition include a backinglayer 12. Backing 12 is provided to contain the drug and prevent itsloss.

The matrices and devices of this invention can be of any size suitablefor transdermal drug delivery. This encompasses an area of from about0.5 cm² to about 100 cm².

Backing 12 is generally a water-occlusive layer preferably made of asheet or film of a preferably flexible elastomeric material that issubstantially impermeable to the selected drug. The layer is preferablyon the order of 1 micrometer to 100 micrometers in thickness, and may ormay not contain pigment. The layer is preferably of a material thatpermits the device to mimic the contours of the skin and be worncomfortably on areas of skin, such as at joints or other points offlexure, that are normally subjected to mechanical strain with little orno likelihood of the device disengaging from the skin due to differencesin the flexibility or resiliency of the skin and the device. Elastomericmaterials generally present these desired properties. Examples ofelastomeric polymers that are useful for making layer 11 are polyetherblock amide copolymers (e.g., PEBAX copolymers), polyethylene methylmethacrylate block copolymers (EMA) such as NUKRELL polymers,polyurethanes such as PELLATHANE or ESTANE polymers, siliconeelastomers, polyester block copolymers that are composed of hard andsoft segments (e.g., HYTREL polymers), rubber-based polyisobutylene,styrene, and styrene-butadiene and styrene-isoprene copolymers. Polymersthat are flexible but not elastomeric include polyethylene,polypropylene, polyesters, e.g., polyester terephthalate (PET), whichmay be in the form of films or laminates. The preferred polymer used forthe backing will depend on the material or drug incorporated into thedevice and on the nature of any vehicles, solubilizers, or the like thatare used.

In a second embodiment, as shown in FIG. 2, a device 20 can include inaddition to the matrix 11 and backing 12 as just set forth a drugreservoir 21. This reservoir can be a void in which additional drug and(as needed) carrier are lodged or can contain a porous substrate such asa porous polymer or sponge which holds and easily delivers drug to thematrix 11 for continuous administration to the patient.

As previously pointed out, the devices of the invention canadvantageously contain added water-soluble water-absorptive polymer.These materials are added solely to improve long-term wearing propertiesby absorbing moisture from the wearer's skin and are not seen to modifyor enhance the rate of drug delivery.

The water-soluble polymers that can be used in the invention include,for example, polyvinyl alcohol, gelatine, polyacrylic acid, sodiumpolyacrylate, methylcellulose, carboxymethylcellulose,polyvinylpyrrolidone, gum acacia, gum tragacanth, carrageenan, gum guarand the like gums and dextrans. They also include suitable cross-linkedreaction products of these materials which may offer improved cohesion.These water-soluble polymers can be used either singly or incombinations of two or more. These water-soluble polymers can be ofmolecular weights varying from as low as 10,000 to several million(3,000,000). Polyvinyl alcohol and polyvinyl pyrollidone, two preferredpolymers, are commercially available in sizes throughout the range.

Device Composition

The devices of this invention have a matrix composed of acrylatecopolymer and drug. The matrix may also include a water-soluble polymer.

The matrix may, in addition, include one or more selected carriers orexcipients, and various agents and ingredients commonly employed indermatological ointments and lotions. For examples, fragrances,opacifiers, preservatives, antioxidants, gelling agents, perfumes,thickening agents, stabilizers, surfactants, emollients, coloringagents, and the like may be present.

The relative amounts of the components in these compositions can vary agreat deal. For example, the amount of drug or drugs present in thecomposition will depend on a variety of factors, including the diseaseto be treated, the nature and activity of the drug, the desired effect,possible adverse reactions, the ability and speed of the drug to reachits intended target, and other factors within the particular knowledgeof the patient and physician.

In typical embodiments, the matrix will contain from about 0.5% up toabout 25% by weight (based on the total matrix weight) drug; forexample, 1 to 10% by weight estrogen (estradiol) and 1 to 15% by weightprogestogen, (norethindrone acetate) will be present in a preferredpost-menopausal syndrome or contraceptive patch, and 1 to 15% by weightestradiol will be present in a preferred patch releasing only estrogen.

The matrix may be formulated so that the selected drug is containedtherein below saturation, at saturation, or in excess.

The amount of water-soluble polymer may range from 0% (in light of itsoptional character) to as much as 40% by weight. When water-solublepolymer is present, use levels of 2 to 30% by weight are preferred.

It is to be understood that while the invention has been described inconjunction with the preferred specific embodiments thereof, that theforegoing description as well as the examples which follow are intendedto illustrate and not limit the scope of the invention. Other aspects,advantages and modifications within the scope of the invention will beapparent to those skilled in the art to which the invention pertains.

EXAMPLE 1

Monolith matrix systems in accord with this invention and based onestradiol, norethindrone, norethindrone acetate, and levonorgesterolwere prepared by the following procedures: The drug was mixed andsonicated with or without a known skin penetration enhancer (PGML) for10 minutes. Typical polymer solvents, if present, included loweralcohols such as ethanol and isopropanol and lower alkanoic acid esterssuch as ethylacetate. (These solvent materials were later removed duringdrying.) Monsanto GELVA® 737 vinyl acetate acrylate copolymer resinpressure-sensitive adhesive solution was added to the drug-solventmixture and rotated overnight. The drug-solvent-polymer mixture was thencast to about 100 micrometers thickness on a polyester film (#1022release liner). The solvent in the polymer system was evaporated in a75° C. forced air oven for 15 to 20 minutes. The resultant drugreservoir matrix was laminated with another polyester film (3M #1022)For comparison, similar compositions (with and without PGML) wereprepared using Dow Corning silicone as the matrix polymer.

Modified Franz flow-through cells were used for in vitro penetrationstudies which were carried out to determine the efficiency of thepresent matrices at delivering drugs. One of the two polyester layerswas peeled off of the drug matrix layer. The drug matrix layer wasgently pressed onto the stratum corneum of human cadaver skin membrane.This skin membrane with the backing and matrix affixed thereto was thenmounted between the two half-cells and fastened with a clamp. Thereceiver compartment was filled with 0.1% gentamycin in distilled,deionized water and the temperature was maintained at 32° C. Sampleswere taken at preset intervals and assayed by HPLC. The flux wascalculated from the slope of the cumulative amounts of the drug in thereceiver compartment versus time.

The fluxes of estradiol, norethindrone, norethindrone acetate andlevonorgesterol through human cadaver skin are summarized in Table 1.The fluxes for all of the drugs tested (i.e., estradiol, norethindroneacetate, norethindrone and levonorgesterol) were not affected byincorporation of the enhancer (PGML) in the acrylate matrix. However,the fluxes of norethindrone and norethindrone acetate did increasesignificantly when PGML was used in the silicone matrix. Moreimportantly, the fluxes of estradiol, norethindrone and levonorgesterolfrom acrylate copolymer systems without enhancers were all comparable tothose with PGML in the silicon matrix system. Although the flux ofnorethindrone acetate from the acrylate copolymer matrix was low, it maybe due to a higher solubility of norethindrone acetate in the acrylatecopolymer system. Therefore, the low loading (1%) of norethindroneacetate may not have enabled a higher driving force for the diffusion.By this reasoning, the norethindrone flux could be increased byincreasing the drug loading in the polymer matrix until maximumthermodynamic activity is reached. It is an advantage of the presentinvention that since no enhancer need be present, higher thermodynamicactivity can be achieved with less drug.

                  TABLE 1                                                         ______________________________________                                        In Vitro Skin Fluxes of Estradiol                                             and Proqestogens Through Human Cadaver Skin                                   From Polymer Matrix With or Without PGML                                                                  Fluxes                                            Drug        System          (mcg/cm.sup.2 hr)                                 ______________________________________                                        Estradiol (E2)                                                                            E2/PGML/silicone                                                                              0.14 ± 0.05                                                (5:14:81, w/w)                                                                E2/PGML/acrylate                                                                              0.17 ± 0.00                                                (1:14:85)                                                                     E2/acrylate (1:99)                                                                            0.12 ± 0.00                                    Norethindrone                                                                             N/PGML/silcone  0.20 ± 0.02                                    (N)         (1:14:85, w/w)                                                                N/silicone (1:99)                                                                             0.07 ± 0.02                                                N/PGML/acrylate 0.26 ± 0.08                                                (1:14:85)                                                                     N/acrylate (1:99)                                                                             0.24 ± 0.09                                    Norethindrone                                                                             NA/PGML/silicone                                                                              0.54 ± 0.10                                    acetate (NA)                                                                              (1:14:85, w/w)                                                                NA/silicone (1:99)                                                                            0.17 ± 0.00                                                NA/PGML/acrylate                                                                              0.06 ± 0.03                                                (1:14:85)                                                                     NA/acrylate     0.05 ± 0.01                                    Levonorgesterol                                                                           LG/PGML/silicone                                                                              0.09 ± 0.02                                    (LG)        (1:14:85), w/w)                                                               LG/PGML/acrylate                                                                              0.22 ± 0.02                                                (1:14:85)                                                                     LG/acrylate (1:99)                                                                            0.17 ± 0.04                                    ______________________________________                                    

EXAMPLE 2

A series of monolith systems of norethindrone acetate was prepared bythe following procedures. Norethindrone acetate was mixed and sonicatedwith solvents and with or without enhancers (PGML and dipropylene glycolmonoethyl ether "Transcutanol"(TC)) for 10 minutes. A solution ofacrylate copolymer pressure-sensitive adhesive was added to thedrug-vehicle mixture and rotated overnight.

The drug-solvent-polymer mixture was then cast on a polyester film (3M#1022 release liner). The solvent in the polymer system was thoroughlyevaporated in a 75° C. forced air oven for 15-20 minutes. The resultantdrug reservoir polymer matrix was laminated with another polyester film(3M #1022).

The in vitro permeation studies and data analyses were the same as inExample 1. Again, the fluxes of norethindrone acetate without enhancerswere comparable to those with enhancers in the polymer matrix (Table 2).The results also show that in the acrylate matrix, the fluxes ofnorethindrone acetate were essentially independent of the presence ofenhancers. Acrylate matrices without enhancers gave fluxes which arecomparable to fluxes possible in conventional silicone matrices onlywith added enhancers.

                  TABLE 2                                                         ______________________________________                                        In Vitro Skin Fluxes of Norethindrone Acetate                                 From Polymer Matrix With and Without Enhancers                                                  Fluxes                                                      System            (mcg/cm.sup.2 /hr)                                          ______________________________________                                        NA/PGML/silicone  0.19 ± 0.03                                              (2/10/88, w/w)                                                                NA/TC:PGML/acrylate                                                                             0.18 ± 0.02                                              (4/10/86, w/w)                                                                NA/PGML/acrylate  0.14 ± 0.02                                              (4/10/86, w/w)                                                                NA/acrylate       0.15 ± 0.03                                              (4/96, w/w)                                                                   ______________________________________                                    

EXAMPLE 3

A series of prototype systems was made. The drug reservoir layers wereprepared as described in Example 2. However, 20% PVP (BASF, K-30) wassuspended with the drugs (E2 and NA) in the polymer solution (Morstik607) with addition of isopropanol. The drugs, PVP, polymer and solventswere then rotated overnight and a homogeneous solution was obtained. Auniform drug reservoir matrix was then cast on a polyester film (3M#1022). The solvent in the system was evaporated in a 75° C. forced airoven for 30 minutes. After cooling, the reservoir layer was laminatedwith a layer of polyisobutylene to an elastomeric backing membrane(Bertek #438, #810, or 3M 166) or laminated directly to a second layerof 3M #1022 polyester.

The in vitro permeation studies and data analyses were the same as inExample 1. The results show that in acrylate systems, the fluxes of bothestradiol and norethindrone acetate were high without employingenhancers (Table 3). The fluxes of the drugs increased as the percentageof drug increased in these systems. The fluxes reached maximum when 4%estradiol and 10% norethindrone acetate were present in the drugmatrices. The flux of 2% estradiol in the system was 0.25 mcg/cm² /hr,which is comparable to the commercial estrogen patches which includepermeation enhancers. The flux of 10% norethindrone acetate reached 0.76mcg/cm² /hr, which indicates that effective levels of progestogens canbe delivered from the system as well. The fluxes were comparable whetherthe backing material used was an occlusive polyester film or combinedlayers of PIB and an occlusive elastomeric layer.

                  TABLE 3                                                         ______________________________________                                        In Vitro Skin Fluxes of Estradiol and Norethindrone                           Acetate from Acrylate Matrix Systems with                                     Polyvinylpyrrolidone Incorporated                                             System                                                                                     Backing   Fluxes (mcg/cm.sup.2 /hr)                              Drug Reservoir                                                                             Layer     Estradiol Norethindrone                                ______________________________________                                        E2/NA/PVP/acrylate                                                                         Polyester 0.25 ± 0.03                                                                          0.38 ± 0.06                               (2/5/20/73, w/w)                                                              E2/NA/PVP/acrylate                                                                         PIB & 3M  0.28 ± 0.04                                                                          0.40 ± 0.04                               (2/5/20/73, w/w)                                                                           166                                                              E2/NA/PVP/acrylate                                                                         PIB &     0.27 ± 0.01                                                                          0.39 ± 0.00                               (2/5/20/73, w/w)                                                                           Bertek 428                                                       E2/NA/PVP/acrylate                                                                         Polyester 0.50 ± 0.13                                                                          0.76 ± 0.17                               (4/10/20/66, w/w)                                                             E2/NA/PVP/acrylate                                                                         PIB & 3M  0.43 ± 0.05                                                                          0.64 ± 0.05                               (4/10/20/66, w/w)                                                                          166                                                              E2/NA/PVP/acrylate                                                                         PIB &     0.39 ± 0.07                                                                          0.58 ± 0.11                               (4/10/20/66, w/w)                                                                          Bertek 810                                                       ______________________________________                                    

EXAMPLE 4

In vitro Franz flow-through cells were used to determine the penetrationof mixtures of norethindrone acetate and estradiol in an acrylate matrixsystem. The system was similar to Example 3. The drug reservoir layerwas made with 2% estradiol, 10% norethindrone acetate and 20% PVP (BASF,K-30) in Morstik acrylate pressure-sensitive adhesive (#607). Thebacking layer contained an occlusive PIB layer and an elastomeric layer(Bertek 810). The in vitro skin fluxes for both drugs during a 7 dayperiod are presented in FIG. 3. This figure shows that the flux of bothdrugs reached steady state within 24 hours and then maintained at steadystate for the rest of the seven day permeation study. The average fluxfor estradiol was 0.21±0.06 (mcg/cm² /hr) while the average flux fornorethindrone acetate was 0.62±0.16 (mcg/cm² /hr) These values suggestthat sufficient amounts of estradiol and norethindrone acetate can bedelivered without incorporation of an enhancer.

EXAMPLES 5-8

The experiments of Example 4 are repeated making changes in thecomposition of the reservoir:

In Example 5, the Morstik 607 is replaced with Monsanto GELVA® 737.

In Example 6, the Morstik 607 is replaced with a 4:1 mixture of GELVA®737:GELVA® 788.

In Example 7, the Morstik 607 is replaced with a 9:1 mixture of GELVA®737:GELVA® 788.

In Example 8, the PVP is replaced with similar levels ofpolyvinylalcohol.

In each case favorable results similar to those seen in Example 4 areattained.

What is claimed is:
 1. A transdermal drug delivery device foradministering at least one steroid drug to an area of skin or mucosa,wherein the device consists of a first layer laminated to a secondlayer, whereinsaid first layer consists of a layer of a backing materialwhich is substantially impermeable to the at least one steroid drug; andsaid second layer consists essentially of a therapeutically effectiveamount of the at least one steroid drug, and an adhesive matrix whereinsaid second layer is essentially free of a skin penetration rateenhancer, and wherein the adhesive matrix comprises a copolymer of2-ethylhexyl acrylate and at least one comonmer selected from the groupconsisting of vinyl acetate, acrylic acid, and methyl acrylate.
 2. Thedevice of claim 1, wherein the adhesive resin comprises a copolymer of2-ethylhexyl acrylate and vinyl acetate.
 3. The device of claim 2,wherein the copolymer comprises approximately 70 wt. % 2-ethylhexylacrylate and approximately 30 wt. % vinyl acetate.
 4. The device ofclaim 2, wherein the copolymer comprises approximately 72 wt. %2-ethylhexyl acrylate and approximately 28 wt. % vinyl acetate.
 5. Thedevice of claim 1, wherein the adhesive matrix comprises a firstcopolymer of approximately 70 wt. % 2-ethylhexyl acrylate andapproximately 30 wt. % vinyl acetate, and a second copolymer ofapproximately 72 wt. % 2-ethylhexyl acrylate and approximately 28 wt. %vinyl acetate.
 6. The device of claim 1, wherein the adhesive matrixcomprises a copolymer of 2-ethylhexylacrylate, methyl acrylate, acrylicacid, and vinyl acetate.
 7. The device of claim 6, wherein the adhesiveresin comprises approximately 85 wt. % 2-ethylhexyl acrylate, 10 wt. %methyl acrylate, 3 wt. % acrylic acid, and 2 wt. % vinyl acrylate. 8.The device of claim 1, wherein the steroid drug is an estrogen.
 9. Thedevice of claim 8, wherein the estrogen is estradiol.
 10. The device ofclaim 1, wherein the steroid drug is s progestogen.
 11. The device ofclaim 10, wherein the progestogen comprises norethindrone ornorethindrone acetate.
 12. The device of claim 1, wherein the drugcomprises a mixture of an estrogen and a progestogen.
 13. A transdermaldrug delivery device for administering at least one steroid drug to anarea of skin or mucosa, wherein the device consists of a first layerlaminated to a second layer, whereinsaid first layer consists of a layerof a backing material which is substantially impermeable to the at leastone steroid drug; and said second layer consists essentially of atherapeutically effective amount of the at least one steroid drug and anadhesive matrix, wherein said second layer is essentially free of a skinpenetration rate enhancer, and wherein the adhesive matrix comprises awater soluble polymer, a copolymer of 2-ethylhexyl acrylate and at leastone comonomer selected from the group consisting of vinyl acetate,acrylic acid, and methyl acrylate.
 14. A transdermal drug deliverydevice for administering at least one steroid drug to an area of skin ormucosa, wherein the device consists of:(a) a layer of backing materialwhich is substantially impermeable to the at least one steroid drug; (b)a matrix layer essentially free of a skin penetration rate enhancer saidmatrix consisting essentially of a therapeutically effective amount ofthe at least one steroid drug and a body of an adhesive resin, andwherein the adhesive resin comprises a copolymer of 2-ethylhexylacrylate and at least one comonomer selected from the group consistingof vinyl acetate, acrylic acid, and methyl acrylate; and (c) between thebacking material and matrix, a drug reservoir for delivering additionalamounts of the at least one steroid drug to the adhesive matrix.
 15. Thedevice of claim 14, wherein a polymer of the matrix is a water-solublepolymer.
 16. The device according to claim 1 wherein the drug isdissolved in the matrix.
 17. The device according to claim 1 wherein thedrug is dispersed in the matrix.
 18. The device according to claim 8wherein the estrogen is ethinyl estradiol.
 19. The device according toclaim 1 wherein the steroid drug is present in a concentration below thesaturation amount.
 20. The device according to claim 1 wherein thesteroid drug is present in a concentration at the saturation amount. 21.The device according to claim 1 wherein the steroid drug is present in aconcentration above the saturation amount.
 22. The transdermal drugdelivery device according to claim 1 wherein the device is of from about0.5 cm² to 100 cm².
 23. The transdermal drug delivery device accordingto claim 1 wherein the drug is present in an amount of from about 0.5%to about 25% of the total matrix weight.
 24. The device of claim 13,wherein the water-soluble polymer is polyvinyl alcohol.
 25. The deviceaccording to claim 13 wherein the water soluble polymer is polyvinylpyrrolidone.